Abstract: Vapour phase polymerised (VPP) polybithiophene (PBTh) on glassy carbon is revealed to be an efficient photo-electrocatalytic electrode for the hydrogen evolution reaction (HER). An onset potential of -0.03 V vs SCE for the HER is observed on illumination using visible light in 0.1 mol L^-1 phosphate buffer at pH 6.9, 600 mV lower in energy than E₀. Hydrogen evolution is confirmed using gas chromatography with a calculated faradaic efficiency of 34 % when holding at a potential of -0.5 V. Importantly, this process occurs without platinum and under neutral aqueous conditions thus revealing a significant but overlooked application for PBTh: a potential low-cost cathode material for the splitting of water.

Ng, Chun H.;[1] Winther-Jensen, Orawan;[1] Kolodziejczyk, Bartlomiej;[1] Ohlin, C. André;[2] Winther-Jensen, Bjørn[1] Photo-electrocatalytic H₂ evolution on poly(2,2'-bithiophene) at neutral pH. Int. J. Hydrogen Energy, 2014, 39(23), 18230-18234. Link.

1. Department of Materials Engineering, Monash University, Vic 3800, Australia
2. School of Chemistry, Monash University, Vic 3800, Australia

Abstract: Electronic-structure calculations show that the epsilon-isomer of the polyoxoaluminate ion in the Keggin structure [AlO₄(Al(OH)₂(H₂O))₁₂]⁷⁺ is the thermodynamically favoured one. Direct interconversion between the epsilon- and delta-isomers via cap rotation has a prohibitively high energy barrier in vacuo, suggesting that isomerisation in solution either proceeds via a dissolution-precipitation pathway, or that solvation and/or coordination to counterions reduces the barrier significantly. The implications for the formation of the [Al₂O₈Al₂₈(OH)₅₆(H₂O)₂₆]¹⁸⁺ ion is discussed.

Ohlin, C. André;[*,1] Rustad, James R.;[2] Casey, William H.[3,4] The energetics of isomerisation in Keggin-series aluminate cations Dalton Trans., 2014, 43(39), 14533-14536. Link.

1. School of Chemistry, Monash University, Vic 3800, Australia
2. Sullivan Park Research Center, Corning Inc., One Science Center Drive, Corning, NY 14831
3. Department of Chemistry, University of California, Davis, CA, USA
4. Department of Earth and Planetary Sciences, University of California, Davis, CA, USA

Abstract: A non-magnetic piston-cylinder pressure cell is presented for solution-state nuclear magnetic resonance (NMR) spectroscopy at geochemical pressures. The probe has been calibrated up to 20 kbar using in situ ruby fluorescence and allows for the measurement of pressure dependencies of a wide variety of NMR-active nuclei with as little as 10 μL of sample in a micro-coil. Initial ¹¹B NMR spectroscopy of the H₃BO₃^- catechol equilibria reveals a large pressure-driven exchange rate and a negative pressure-dependent activation volume, reflecting increased solvation and electrostriction upon boron-catecholate formation. The inexpensive probe design doubles the current pressure range available for solution-NMR spectroscopy and is particularly important to advance the field of aqueous geochemistry. Selected as a Very Important Paper and cover.

Pautler, Brent G.;[1] Colla, Christopher A.;[2] Johnson, Rene L.;[1] Klavins, Peter;[3] Harley, Stephen J.;[4] Ohlin, C. André;[5] Sverjensky, Dimitri A;[6,7] Walton, Jeffrey;[8] Casey, William H.[1,2] A high-pressure NMR probe for aqueous geochemistry Angew. Chem. Int. Ed., 2014, 53(37), 9788-9791. Link and Back cover.

See also press releases at Monash University, UC Davis, and youtube.com.

1. Department of Chemistry, University of California, Davis, CA, USA
2. Department of Earth and Planetary Sciences, University of California, Davis, CA, USA
3. Department of Physics, University of California, Davis, USA
4. Energetic Materials Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
5. School of Chemistry, Monash University, Vic 3800, Australia
6. Department of Earth and Planetary Sciences, John Hopkins University, Baltimore, MD, USA
7. Geophysical Laboratory, Carnegie Institution of Washington, DC, USA
8. NMR facility, University of California, Davis, CA, USA

Abstract: This review covers recent advances in the understanding of the in vitro and in vivo effects of decavanadate, [V₁₀O₂₈]^6-, particularly in mitochondria. In vivo toxicological studies involving vanadium rarely account for the fact that under physiological conditions some vanadium may be present in the form of the decavanadate ion, which may behave differently from ortho- and metavanadates. It has for example been demonstrated that vanadium levels in heart or liver mitochondria are increased upon decavanadate exposure. Additionally, in vitro studies have shown that mitochondrial depolarization (IC₅₀, 40 nM) and oxygen consumption (IC50, 99 nM) are strongly affected by decavanadate, which causes reduction of cytochrome b (complex III). We review these recent findings which together suggest that the observed cellular targets, metabolic pathway and toxicological effects differ according to the species of vanadium present. In addition, the toxicological effects of decavanadate depend on several factors such as the mode of administration, exposure time and type of tissue.

Aureliano, M.;[1,2] C. André Ohlin[3] Decavanadate in vitro and in vivo effects: facts and opinions. J. Inorg. Biochem., 2014, 137, 123-130. Link

1. DCBB, FCT, University of Algarve, 8005-139 Faro, Portugal.
2. CCMar, University of Algarve, 8005-139 Faro, Portugal.
3. School of Chemistry, Monash University, Vic 3800, Australia.

Abstract: The abundance and low toxicity of manganese has led us to explore the application of manganese complexes as redox mediators for dye sensitized solar cells (DSCs), a promising solar energy conversion technology which mimics mimics some of the key processes in photosynthesis during its operation. In this paper, we report the development of a DSC electrolyte based on the tris(acetylacetonato)-manganese(III)/(IV), [Mn(acac)3]0/1+, redox couple. PEDOT-coated FTO glass was used as counter electrode instead of the conventionally used platinum. The influence of a number of device parameters on the DSC performance was studied, including the concentration of reduced and oxidized mediator species, the concentration of specific additives (4-tert-butylpyridine, lithium tetrafluoroborate, and chenodeoxycholic acid) and the thickness of the TiO2 working electrode. These studies were carried out with a new donor-π-acceptor sensitizer K4. Maximum energy conversion efficiencies of 3.8 % at simulated one Sun irradiation (AM 1.5 G; 1000 W m-2) with an open circuit voltage (VOC) of 765 mV, a short-circuit current (JSC) of 7.8 mA cm-2 and a fill factor (FF) of 0.72 were obtained. Application of the commercially available MK2 and N719 sensitizers resulted in an energy conversion efficiency to 4.4 % with a VOC of 733 mV and a JSC of 8.6 mA cm-2 for MK2 and a VOC of 771 mV and a JSC of 7.9 mA cm-2 for N719. Both dyes exhibit higher incident photon to current conversion efficiencies (IPCEs) than K4.

Perera, Ishanie Rangeeka;[1] Gupta, Akhil;[2,3] Xiang, Wanchun;[1] Daeneke, Torben;[2] Bach, Udo;[2,3,4] Evans, Richard A.;[2] Ohlin, C. André Ohlin;[1] Spiccia, Leone[1] Introducing Manganese Complexes as Redox Mediators for Dye-sensitized Solar Cells Phys. Chem. Chem. Phys., 2014, 24(16), 12021-12028.

1. School of Chemistry, Monash University, Vic 3800, Australia
2. CSIRO Materials Science and Engineering, CSIRO Future Manufacturing Flagship, Clayton South, Vic 3169, Australia
3. Department of Materials Engineering, Faculty of Engineering, Monash University, Vic 3800, Australia
4. Tech Fellow, The Melbourne Centre for Nanofabrication, Vic 3168, Australia

Abstract: Reaction of [Ir(COD)(py-ItBu)]⁺ (py-ItBu = 3-tert-butyl-1-picolylimidazol-2-ylidene) with acetonitrile results in reversible intramolecular C-H bond activation of the NHC ligand and formation of [Ir(eta2:eta1-C8H13)(py-ItBu')(NCMe)]⁺. Coordinated COD acts as an internal hydride acceptor and acetonitrile coordination offsets the otherwise unfavourable thermodynamics of the process.

Wheatley, James E.;[1] Ohlin, C. André;[2] Chaplin, Adrian B.[1] Solvent promoted reversible cyclometalation in a tethered NHC iridium complex Chem. Commun., 2014, 50, 685-687.

1. Department of Chemistry, University of Warwick, UK
2. School of Chemistry, Monash University, Vic 3800, Australia